Control system for vapor-electric valves



y 28, 1942- J. H. cox ETAL 2,291,092

corimoh SYSTEM FOR VAPOR-ELECTRIC VALVES Filed Nov. 26, 1941 WITNESSES: INVENTOR$ J'aseph H Cox and 10 MW ATTORNEY I ceases to flow tothe make-alive electrode upon contact with the cathode [6 during normal op- Patentecl July 28, 1942 I i UNITED STATES PATENT OFFICE 2,291,092 CONTROL SYSTEM FOR VAPOR-ELECTRIC VALVES Joseph H. Cox, Forest Hills, and Henry C. Myers, Irwin, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa... a corporation of Pennsylvania Application November 26, 1941, Serial No. 420,532 4 Claims. 175-354) Our invention relates to a vapor-electric detric conversion system according to our invenvice and particularly to a control system for setion. curing control of the device with a minimum ex- In the illustrative embodiment of our invenpenditure of control energy. tion, the polyphase alternating current circuit In the development of make-alive type valves. 5 I0 is connected to a direct current circuit II it has been found that the rating of the valves by means'of a rectifier transformer l2. A suitc-an be materially increased by providing an anable disconnecting switch 52 is placed between ode shield about the anode for rapidly deionizthe alternating current circuit I 0 and the pri-' ing the anode space. However, when such an mary winding I3 of the rectifier transformer l2. anode shield is utilized, it'has 'been found de- The direct current circuit II is preferably prosirable to apply excitation potential to the anvided with a disconnecting switch 12 which may ode shield to insure rapid pick-up of the curbe of the high-speed reverse-current or so-called rent-carrying arc to the anode. bucking-bar" type. The valve phase terminals The application of potential to the anode shield I to 8 of the secondary winding M of the transrequires the use of a greater amount of control 15 former it are connected to the anodes la to to energy n energizing the tube. However, it is of the make-alive type valves I5, which control very desirable that the application of control the flow of energy between the circuits l0 and II. potential to the make-alive electrode should ter- Each of the make-alive type valves l5 comminate as soon as possible after the formation prises a vaporizable reconstructing cathode oi the cathode spot as is possible in order to usually of mercury or other metal which is liquid conserve e y applied to the make-alive elecat the operating temperatures of the valves. Cotrode and also reduce the heating and possible operating with the cathode i6 is one of the anerosion of the make-alive electrode bythe exodes lw6a spaced from and insulated from cessive lent. the cathode it. The anodes are usually sur- According to our invention, we not only serounded by a suitable shield l1 usually in the cure the termination of the make-alive energy form of a graphite basket which serves to debut also conserve the energy otherwise utilized ionize the space immediately adjacent to the inenergizing'the anode shields by energizing both anode and thus improve the commutating charthe make-alive electrode and'the anode shield acteristics of the valve. The initiat o of the from the same soure of control potential and current spot is obtained by a make-alive elecsupplying means whereby the make-alive energy trode |'8, a portion of which is in permanent the formation 01' the cathode spot and the new eration of the device. All of these elements are of current to the anode shield. -We accomplish preferably contained in a suitable evacuated this result by providing an impedance in series chamber or container l9. with the make-alive electrode and connecting the The application of control potentials to the anode shield in parallel with the make-alive elecvarious make-alive electrodes l8 and the anode trode and its associated impedance. Therefore, shields I9 is supplied by a control circuit preswhen the cathode spot is formed, an excitation ently to be described. The preferred control are will pick up from the anode shield short cir- 40 circuit comprises a source of polyphase altercuiting the flow of energy to the make-alive nating current having the same frequency as e- Y the potential appliedto the rectifier transformer It is accordingly an object of our invention l2. For convenience, we have shown this poto provide a control system wherein a single tential as being derived directly from the altersourcesupplies energy to both the make-alive 4 nating current circuit l0.

electrode and the anode shield. An suitable impulsing device energized from It is a further object of our invention to prothe control current source may be-utilized for vide a control system in which the flow of energy supplying impulses to the make-alive electrodes, to the anode shield will relieve the duty on the we prefer to utilize a wave distorter circuit emmfike'elive electrode. bodying a saturable core reactor for controlling other O j advantages O 0111' invenithe wave-shape applied to the make alive election will be apparent from the following detrodes l8. tailed description, taken in conjunction with For purposes of illustration, we have disclosed the accompanying drawing, in which the single the rectifier transformer secondary H as being figure is a schematic illustration of a vapor-elecof the double three-phase type in which pairs of valves, such as I and l, 3 and 5, 2 and 5, have valves which are alternately energized during normal operation .of the device. In order to make full use of the wave distorter circuits, we provide an excitation transformer 20 having a plurality of secondary windings 2| electrically insulated from each other and corresponding in number to the pairs of valves as energized by the main transformer l2. Each of the secondary windings 2| has associated with it a wave distorter circuit comprising a substantially linear impedance 22 connected in series with the winding 2|, a capacitor 23 connected inv shunt across the winding 2| and the linear impedance 22 so that the capacitor 23 is charged through the linear impedance 22 then when the potential of the winding 2| reaches a value suflicient to supply saturating current to the saturable reactor 24 connected in series with the linear reactor the capacitor discharges through the saturable reactor. and assists in producing a high peak of current with the minimum capacity of transformer 2. The opposite terminals of this wave distorting network are connected to the respective make-alive electrodes ll of a pair of valves by means of a. series rectifier or asymmetrical contorter circuit through one of the shunt asymmetric conductors 26. The series shunt asymmetric conductors 25-46 provide a circuit in which two asymmetric conductors are connected in conducting relation from the cathode l5 to the make-alive electrode l8 and in which the controlled impulses are impressed intermediate the asymmetric conductors 25-28, the connection 3| for the relieving anode l'i being conveniently made also at the same point intermediate the asymmetric conductors at which the wave distorter circuit is connected.

While for purposes of description we have shown and described a specific embodiment of our invention,'lt will be apparent that changes and modifications can be made therein without departing from the true spirit of our invention or the scope of the appended claims.

We claim as our invention:

1. In combination, an electric current translating system for transferring current between a poiyphase alternating current circuit and a nector 25. A suitable return circuit is provided by connecting a second asymmetrical conductor 26 in shunt with each make-alive electrode l8 and its associated series rectifier 25.

The connection and phase relation of the impulsing'transformer 20 is selected to produce the make-alive control impulse at substantially the desired instant in the make-alive type valves. However, it is desirable to provide a phase shifter such as the induction phase shifter 30 to correctly determine the phase position or to change the phase position of the make-alive impulses.

In the operation of this system, the potential of thewinding 2| flows through the impedance 22 charging the capacitor 23 until the potential of the coil 2| rises above the potential required to saturate the core of the saturable reactor 24 at which time a pulse of current will flow through the reactor and, depending upon the polarity, will be selectively applied to the proper makealive electrode I! by the series shunt rectlflers 25-25. The reversal ofpolarity of the secondary winding 2| will produce an impulse of the opposite polarity which will then tire the alternate valve of the connected pair. However, it is desirable to relieve the make-alive electrode I! of all excess current flow after the cathode spot has been formed. We accomplish this by a connection-Il intermediate the series shunt rectiflers 25-25 to the anode shield ll. With this connection, as soon as the make-alive current has initiated a cathode spot, current will flow to the anode shield l1 and establish an excitation are between the cathode l5 and shield l1. Because of the impedance of the make-alive electrode l8 and its series asymmetric conductor 25, the major portion of the current will appear in the keepalive excitation. However, if it is found that too large a current still flow through the make-alive electrode It, a suitable impedance I2 may be placed in series with the make-alive electrode is, preferably between the make-alive electrode l8 and its series connected asymmetric conductor 25 in order to increase the current flowing to the anode shield l'l.

As will be obvious from an inspection of the drawing, the current flowing through a make- .alive electrode II flows through the cathode l6 and back to the opposite side of the wave disdirect current circuit including a plurality of pairs of vapor-electric valves of the make-alive type, the valves of each pair being alternately conducting, each of said valves including a vaporizable reconstructing cathode, an anode, a make-alive electrode and an anode shield in an evacuated container, a control circuit comprising a source of poiyphase alternating current of the same frequency as the alternating current circuit, means for producing a plurality of electrically insulated phase windings corresponding to the pairs of vapor-electric valves, an impulsing circuit energized by each phase winding, two asymmetric conductors connected in series conductive relation from each cathode to its associated make-alive electrode, connections from the impulsing circuit to a. point intermediate the asymmetric conductors of a pair of.valves and connections from the impulsing circuit to the anode shields of said pair of valves.

2. In an electric translating system using a plurality of vapor-electric valves of the makealive type each valve including a cathode, an anode, an anode shield and a make-alike electrode, a control system comprising a source of control potential, means energized from said source for producing control impulses having an efiective value of potential over a period less than a half cycle of the control potential, connections including an asymmetric conductor in series with the make-alive electrode and a second asymmetric conductor in shunt with the make-alive electrode and the first asymmetric conductor for selectively impressing the impulses on th makealive electrode and a connection independent of said asymmetric conductors for impressing the control impulses on the anode shield.

3. In combination an electric current converter having a plurality of vapor-electric valves of the make-alive type, each valve including a cathode, a make-alive electrode in contact with said cathode, an anode in spaced insulated relation to said cathode, and an anode shield about the anode, a control system comprising a source of poiyphase control potential, means for providing a plurality of substantially independent phase windings, a wave distorter circuit associated with each phase winding, means including said wave distorter circuits and a plurality of asymmetric conductors for selectively impressing the output of said phase windings on said make-alive electrodes and a connection intermediate said asymmetric conductors for impressing the potential asymmetric conductor in series with the makealive electrode, a second asymmetric conductor in shunt with said first-mentioncd asymmetric conductor and said make-alive electrode and a connection from a point intermediate said asymmetric conductors to said ancde shield.

JOSEPH H. COX. HENRY C. MYERS. 

